[GongHeng2017]

Root Cause Analysis

The sidebar thumbnail rendering pipeline has a resolution mismatch: PageRenderThread::execNextDocPageThumbnailTask() (PageRenderThread.cpp:817) hardcoded the render resolution at 174×174, while the display side (ThumbnailDelegate::paint()) draws the thumbnail at 174 * pixScale * dpr. When the sidebar is widened (pixScale > 1.0) or on HiDPI displays (dpr > 1.0), Qt upscales the 174px source image, causing visible blur. The root cause is that the pixScale factor — already available on the display side via the adaptScale property — was never propagated to the render side.

Fix Approach

Added a pixScale field to DocPageThumbnailTask (default 1.0 for backward compatibility). Both task creation sites in SideBarImageViewModel now read adaptScale from the parent widget and assign it to the task. The render call in execNextDocPageThumbnailTask() computes the actual render size as 174 * pixScale * dpr, matching the display-side drawing dimensions and eliminating upscaling.

Change Safety Assessment

Code Safety

• Risk Level: Medium
• Target code is the product of a prior fix (commit 5e36ac0) that introduced pixScale on the display side but did not propagate it to the render side; this change supplements rather than reverts that fix
• DocPageThumbnailTask is an internal struct (not public API); the new pixScale field defaults to 1.0, preserving existing behavior when unset

Business Impact Scope

• Thumbnail rendering — sidebar PDF page thumbnails are affected. Users will see sharper thumbnails when the sidebar is widened or on HiDPI displays. No impact on document rendering, annotation, or other features.
• Affected callers: SideBarImageViewModel::data() and SideBarImageViewModel::onUpdateImage() (task creation), PageRenderThread::execNextDocPageThumbnailTask() (render execution)

Verification Suggestion

Focus regression testing on thumbnail clarity at various sidebar widths and system zoom levels (100%, 125%, 150%, 200%), plus HiDPI 2x displays. Verify dark-theme thumbnail inversion and XPS document thumbnail performance are unaffected.

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根因分析

侧边栏缩略图渲染管线存在分辨率不匹配问题：PageRenderThread::execNextDocPageThumbnailTask()（PageRenderThread.cpp:817）硬编码渲染分辨率为 174×174，而显示侧（ThumbnailDelegate::paint()）按 174 * pixScale * dpr 绘制。当侧边栏变宽（pixScale > 1.0）或在 HiDPI 显示器上（dpr > 1.0）时，Qt 将 174px 源图像放大，导致明显模糊。根因是显示侧已通过 adaptScale 属性获取的 pixScale 因子从未传递到渲染侧。

修复方案

在 DocPageThumbnailTask 中新增 pixScale 字段（默认 1.0，保证向后兼容）。SideBarImageViewModel 的两个 task 创建点从父组件的 adaptScale 属性读取并赋值。execNextDocPageThumbnailTask() 中的渲染调用按 174 * pixScale * dpr 计算实际渲染尺寸，与显示侧绘制尺寸匹配，消除放大模糊。

改动安全评估

代码安全评估

• 风险等级: 中风险
• 目标代码是历史修复（commit 5e36ac0）的产物，该修复在显示侧引入了 pixScale 缩放但未同步到渲染侧；本次改动补充而非撤销该修复
• DocPageThumbnailTask 是内部结构体（非公开 API）；新增 pixScale 字段默认 1.0，未赋值时行为不变

业务影响范围

• 缩略图渲染 — 侧边栏 PDF 页面缩略图受影响。用户在侧边栏变宽或 HiDPI 设备上会看到更清晰的缩略图。不影响文档渲染、批注等其他功能。
• 受影响调用方：SideBarImageViewModel::data() 和 SideBarImageViewModel::onUpdateImage()（task 创建），PageRenderThread::execNextDocPageThumbnailTask()（渲染执行）

验证建议

回归测试重点：不同侧边栏宽度和系统缩放比例（100%、125%、150%、200%）下的缩略图清晰度，以及 HiDPI 2x 显示器上的表现。验证深色主题缩略图反色和 XPS 文档缩略图性能不受影响。

Summary by Sourcery

Match sidebar thumbnail rendering resolution to its display size so thumbnails remain sharp across sidebar widths and HiDPI displays.

Bug Fixes:

• Render sidebar thumbnails at display-aware resolutions to prevent blur when sidebar scaling or display pixel density increases.

Enhancements:

• Propagate the sidebar scaling factor through thumbnail tasks while preserving the existing default behavior for callers that do not provide it.

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: GongHeng2017

The full list of commands accepted by this bot can be found here.

Details

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• debian/deepin/OWNERS

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[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

This PR fixes blurry sidebar thumbnails by carrying the UI's adaptScale into DocPageThumbnailTask and using it with the device pixel ratio to size both thumbnail rendering and associated image rectangles, while retaining 1.0-scale backward-compatible behavior.

Sequence diagram for display-aware sidebar thumbnail rendering

sequenceDiagram
    participant UI as SideBarImageViewModel
    participant Queue as PageRenderThread
    participant Renderer as DocumentRenderer
    participant View as ThumbnailDelegate

    UI->>UI: property(adaptScale)
    UI->>Queue: appendTask(DocPageThumbnailTask.pixScale)
    Queue->>Queue: execNextDocPageThumbnailTask()
    Queue->>Queue: compute renderSize = 174 * pixScale * devicePixelRatio()
    Queue->>Renderer: getImage(index, renderSize, renderSize)
    Queue->>Renderer: getImageObjectRects(index, renderSize, renderSize)
    Renderer-->>Queue: image and imageRects
    Queue-->>View: sigDocPageThumbnailTaskFinished()
    View->>View: paint at 174 * pixScale * dpr

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File-Level Changes

Change	Details	Files
Propagate the sidebar display scale into thumbnail rendering so generated images match their on-screen pixel dimensions.	Added a defaulted pixScale field to thumbnail tasks. Captured adaptScale when tasks are created in both model paths. Computed render and image-object-rectangle sizes as 174 * pixScale * devicePixelRatio(). Kept thumbnail and dark-theme image overlays at identical dimensions.	reader/browser/PageRenderThread.h reader/browser/PageRenderThread.cpp reader/sidebar/SideBarImageViewModel.cpp

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